On my carter 172, the suction side is -10 an. Is this a o-ring thread, as it doesn't match npt? Does anybody know who makes a 3/8 o-ring to 3/8 barb, so I can use some rubber hose and clamps to connect to the tank line. Thanks for the help, Dave.

its straight thread with a sealing washer.

Thank you, I finally found a post other then your carter 172 mod's that also answered the ?. Hopefully I can find the right fitting in the morning. Dave.